Determination of riboflavin by using UV-vis
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1. To determine the amount of riboflavin in children multivitamin tablet. 2. To compare the value obtain of riboflavin with the published value for the tablet. INTRODUCTION:
Riboflavin also knows as vitamin B2 that has chemical formula of C17H20N4O6 is the water soluble vitamin that means the body was not stored them and also not produce them, the sources of the riboflavin can found in plants or animals tissues such as almonds, organ meats, whole grains, green leafy vegetables milk and etc. Vitamin B2 is very important to the body cause it is involved in the vital metabolic processes in the human body, and it is necessary for the body growth, also can act as antioxidant in order to prevent the free radical that can contributes to the cancer. Besides it also necessary for the energy production were it convert the carbohydrates to the glucose and also convert the vitamin B6 and folate in the form that can use by body.
The lack of the riboflavin in the body can caused slowed growth, digestive problem, and also the swelling and soreness of the throat. While the excess of the riboflavin can contributes to the kidney stones, allergy and sensitive to the light. That why for the children although for the adults it has a limitation of riboflavin intake in daily dietary. According to the Recommended Dietary Allowance (RDA), the children 0-6 months old just need to take 0.4mg for the 17-12 months is 1.0 mg, 1-3 years are 0.5mg, 4-8 years is 0.6mg and for 9-13 years need 0.9mg. Nowadays, there is easy ways for the children that not have unbalance of vitamins in their dietary, because the multivitamins can provides all the useful vitamins for them. Multivitamins is the dietary supplement that contains three or more vitamin and mineral does not included herb, hormones, and drug that form in the tablet, capsule, powder, liquids and also injections.
There is a wide method in order to determine the riboflavin and the one of sufficient method that can used is by using UV-Vis. UV-Vis spectroscopy is based on the selective absorption of electromagnetic radiation in the 180-780nm wavelength range. UV-Vis radiation has sufficient energy to cause transition in bonding electrons and thus, is correlated best with the behavior of bonds and functional groups in the analyte. Absorption in the UV-Vis range is mainly a study of molecules and their electronic transitions. Electron participating directly in bond formation or to unshared,outer electrons that are localized about electronegative atoms that can be promote to a higher energy molecular orbital.UV-Vis spectra can be obtained from organic absorbing species such as transition element ions, lanthanides and actinides as well as inorganic complexes or charge transfer complexes. APPARATUS AND MATERIALS:
volumetric flask, graduated pipette, beaker, mortar and pestle, stirrer , dropper distilled water, 1% ethanoic acid, 1 M NaOH, Riboflavin, multivitamin tablet, glacial acetic acid. PROCEDURE:
Preparation of standard:
A 100 ppm stock standard of riboflavin was prepared by dissolving 0.01 g of riboflavin powder in 100 mL of 1% ethanoic acid. Working standards were prepared by pipetting 0.5 mL, 1.5 mL, 2.5 mL, 3.5 mL, and 4.5 mL aliquots of the standard solution into separate 50 mL volumetric flask and was diluting with the 1% ethanoic acid. Preparation of sample:
One tablet of the children multivitamin was weighed and was grind by the mortar and pestle in order to get the tablet powder. One fifth of the tablet powder was weight accurately and transferred into the 250 mL volumetric flask and was dissolved with 3 mL of 1 M NaOH and glacial acetic acid and was diluting with distilled water. 25 mL of the aliquot was pipette from the 250 mL volumetric flask and was making up in the 250 ml another volumetric flask and 1 in 10 dilutions was further make. The working standards and the sample were measured by using UV-Vis spectrometer at 460 nm wavelength 10 mm quartz cuvette.
In this experiment the UV-Vis was selected as a instrument use for the determination of riboflavin in multivitamin because UV-Vis is a good instrument for the qualitative and also quantitative analysis where for the qualitative UV-Vis cam measure or determine the wavelength at the maximum absorbance which is for the riboflavin the wavelength is 460 nm, for the quantitative UV-Vis can determine the concentration of the sample that containing same compound as a references standard. Beside the structure of the riboflavin that have conjugated structure and also have a chromophores that make it able to use UV-Vis spectrometer. Riboflavin is very sensitive to the presence of direct light, because when riboflavin was exposed to the light it wills decompose and converted to lumiflavin which is the compound that can destroy vitamin C.
that why in preparation of riboflavin solution all the glassware was cover with the aluminum foil and also was done in the dark conditions. Other than that, riboflavin was diluting with the ethanoic acid in order to make it more stable. The results in chart 1 shows that Champs multivitamin has the higher amount of riboflavin content in the tablet is about 0.1155 mg followed by Chewies multivitamin 0.1131 mg and Scott’s 0.0672 mg. The amount of the riboflavin obtain was slightly different with the published value for the tablet where table 4 shows that the amount of the references for the scott’s is 1.5 mg, for the Chewies and Champs were 0.25mg and 0.60mg.
The differences happened maybe due to the some error such as systematic error either it is personal error or instrumental error. Personal error was happened cause by the inattention or carelessness when conducted the experiment, maybe wrong in estimating the level of the liquid with the respect to graduation in pipette when using the pipette for measuring and deliver the sample solution. Besides for the instrument error it maybe cause by the measuring devices that use in this experiment such as pipette, cause it may deliver volume slightly different from the indicated by their graduation. In order to get the exact result all the error must be eliminate or reduced by improved the personal skill in conducted or uses of the instrument or devices also avoid uses the broken devices that can affect the result. CONCLUSION:
As the conclusion the amount of the riboflavin can determine by using UV-Vis spectrometer ,while the amount of the riboflavin per tablet in the multivitamin was calculated is 0.1155 mg for the Champs, 0.0672 mg for the Scott’s and 0.1131 mg for the Chewies multivitamin. From the result we knows that the amount calculated was slightly different with the publish value for the tablets.
1. Vitamin B2 (riboflavin), 16th September 2012 retrieved from; http://www.drweil.com/drw/u/ART02761/vitamin-b2 2. Riboflavin, 15th September 2012, retrieved from; http://www.newworldencyclopedia.org/entry/Riboflavin 3. Multivitamin, 16th September 2012, retrieved from; http://en.wikipedia.org/wiki/Multivitamin 4. Uv-vis spectroscopy, 15th September 2012, retrieve from; http://www.plant.uoguelph.ca/research/homepages/raizada/Equipment/RaizadaWeb%20Equipment%20PDFs/5B.%20UV%20VIS%20theory%20ThermoSpectric.pdf 5. Skoag, D.A., West, D.M., Holler, FJ and Crouch, S.R..,2004. fundamentals of analytical Chemistry. (8th Ed). Thomson Brooks/Cole Publisher